The most common form of cradle used for infants from birth is a bassinet style cradle. This comprises a flat base section with a surrounding wall, and a rectangular mattress is located on top of the base portion.
This provides a flat planar surface upon which the baby sleeps.
Obviously, young infants require a larger amount of sleep, but unfortunately some infants find sleeping somewhat difficult. It is felt that some infants do not cope with the transition from a mother's womb to sleeping in a totally different environment provided by a bassinet.
In the past, a great deal of effort has been expended in comforting infants at the early stages of their life while they are sleeping in such bassinets. Such arrangements include rocking, or providing rhythmic noises, which in some cases has quite beneficial effects.